U.S. patent number 9,347,500 [Application Number 13/501,302] was granted by the patent office on 2016-05-24 for vehicle control device.
This patent grant is currently assigned to NISSAN MOTOR CO., LTD.. The grantee listed for this patent is Tadashi Okuda. Invention is credited to Tadashi Okuda.
United States Patent |
9,347,500 |
Okuda |
May 24, 2016 |
Vehicle control device
Abstract
A first clutch CL1 is disposed between engine Eng and left and
right rear wheels RL, RR, and control of disengaging first clutch
CL1 is performed by setting line pressure PL as an original
pressure and executing F/B control of a piston stroke position. In
this FR hybrid vehicle, when disengaging first clutch CL1, line
pressure increase control to increase line pressure PL to a value
higher than a reference line pressure in advance is started at
least before a piston pressure reaches the reference line pressure,
and line pressure PL is returned to the reference line pressure
when the piston pressure is reduced during this disengagement
operation.
Inventors: |
Okuda; Tadashi (Hadano,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Okuda; Tadashi |
Hadano |
N/A |
JP |
|
|
Assignee: |
NISSAN MOTOR CO., LTD.
(Yokohama-shi, JP)
|
Family
ID: |
43876174 |
Appl.
No.: |
13/501,302 |
Filed: |
October 13, 2010 |
PCT
Filed: |
October 13, 2010 |
PCT No.: |
PCT/JP2010/067906 |
371(c)(1),(2),(4) Date: |
April 11, 2012 |
PCT
Pub. No.: |
WO2011/046124 |
PCT
Pub. Date: |
April 21, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20120199437 A1 |
Aug 9, 2012 |
|
Foreign Application Priority Data
|
|
|
|
|
Oct 14, 2009 [JP] |
|
|
2009-237194 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60K
6/48 (20130101); B60W 20/40 (20130101); B60W
20/00 (20130101); F16D 48/062 (20130101); B60W
10/02 (20130101); F16D 48/04 (20130101); F16D
25/087 (20130101); B60W 10/08 (20130101); B60K
6/547 (20130101); B60W 10/06 (20130101); F16D
2500/3166 (20130101); F16D 2500/7041 (20130101); F16D
2500/1026 (20130101); F16D 2500/10412 (20130101); B60W
2510/0208 (20130101); F16D 2500/3026 (20130101); F16D
2500/3024 (20130101); Y02T 10/6221 (20130101); F16D
2500/1066 (20130101); F16D 2500/70406 (20130101); Y02T
10/62 (20130101); F16D 2500/525 (20130101); Y02T
10/6286 (20130101) |
Current International
Class: |
F16D
25/00 (20060101); B60K 6/48 (20071001); F16D
48/04 (20060101); B60W 10/02 (20060101); B60W
10/06 (20060101); B60W 10/08 (20060101); B60W
20/00 (20160101); F16D 25/08 (20060101); B60K
6/547 (20071001) |
Field of
Search: |
;192/85.57,85.63 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
6176808 |
January 2001 |
Brown et al. |
6499577 |
December 2002 |
Kitamoto et al. |
8092343 |
January 2012 |
Leibbrandt et al. |
|
Foreign Patent Documents
Primary Examiner: Hansen; Colby M
Assistant Examiner: Fluhart; Stacey
Attorney, Agent or Firm: Foley & Lardner LLP
Claims
The invention claimed is:
1. A control apparatus of a vehicle including a driving source and
an automatic transmission that is driven and controlled by a
hydraulic pressure produced from a line pressure as an original
pressure, the control apparatus comprising: a hydraulic clutch
disposed between the driving source and the automatic transmission;
a clutch hydraulic actuator including a piston; a clutch hydraulic
control valve configured to produce a piston pressure from the line
pressure as the original pressure, the piston pressure being
applied to the piston, wherein the piston pressure is limited
substantially to the line pressure; a clutch control section
configured to operate the piston of the clutch hydraulic actuator
to make a stroke to disengage the hydraulic clutch by controlling
the piston pressure as a clutch disengagement hydraulic pressure
such that an actual piston stroke position is conformed with a
target position; an AT control section configured to determine a
reference line pressure on the basis of a necessary hydraulic
pressure to ensure an operation of the automatic transmission; and
a clutch disengagement control section, which controls
disengagement of the hydraulic clutch, configured to: upon
receiving a clutch disengagement command and disengaging the
hydraulic clutch, start line pressure increase control to increase
the line pressure to a value higher than the reference line
pressure at least before the piston pressure reaches the reference
line pressure, and thereby allow the piston pressure to exceed the
reference line pressure; and reduce the line pressure when the
piston pressure is reduced during an operation of disengagement of
the hydraulic clutch.
2. The control apparatus of a vehicle as claimed in claim 1,
wherein the clutch disengagement control section is configured to
set a timing of increasing the line pressure within a predetermined
time width that straddles a timing of starting to increase the
piston pressure.
3. The control apparatus of a vehicle as claimed in claim 2,
wherein the clutch disengagement control section is configured to
set the timing of increasing the line pressure in conformity with
the timing of starting to increase the piston pressure.
4. The control apparatus as claimed in claim 1, wherein the AT
control section is configured to determine the reference line
pressure independently of operation of the hydraulic clutch.
Description
TECHNICAL FIELD
The present invention relates to a control apparatus of a vehicle
including a hydraulic clutch disposed between a driving source and
driving wheels, the control apparatus being configured to set a
piston pressure as a clutch disengagement hydraulic pressure which
is produced from a line pressure as an original pressure by a
clutch hydraulic control valve.
BACKGROUND ART
Conventionally, there has been proposed an automatic clutch control
apparatus in which in a case where an actual clutch stroke does not
reach a target clutch disengagement stroke and it is judged that
flow rate compensation is necessary, a flow rate of fluid to be
supplied to a clutch is increased to compensate for lack of flow
rate by turning on a pump motor (for instance, see Patent
Literature 1).
CITATION LIST
Patent Literature
Patent Literature 1: Japanese Patent Application Unexamined
Publication No. 11-82561
SUMMARY OF INVENTION
However, in the automatic clutch control apparatus of the
conventional art, a detection value of the actual clutch stroke is
received as feedback information, and after it is recognized that
the detection value of the actual clutch stroke does not reach the
target clutch disengagement stroke, the flow rate of fluid is
increased. Thus, the conventional automatic clutch control
apparatus performs feedback control using a closed loop circuit.
Therefore, even in a case where the line pressure as an original
pressure of a clutch hydraulic control valve must be increased when
flow rate compensation is necessary, there will occur a hydraulic
response delay in rise in the line pressure.
As a result, there occurs a problem as follows. Upon disengagement
of the clutch in which the flow rate compensation is necessary, a
delay in rise in necessary flow rate of fluid (a necessary
hydraulic pressure) is caused to thereby prolong the stroke
required time from outputting a clutch disengagement command until
a clutch stroke position reaches a target clutch disengagement
position, thereby causing deterioration in response of clutch
disengagement.
The present invention has been made in view of the above problem.
An object of the present invention is to provide a control
apparatus of a vehicle which is capable of suppressing unnecessary
energy loss and enhancing a response of clutch disengagement
regardless of variation in clutch disengagement necessary pressure
(necessary pressure to disengage a clutch), upon disengaging the
clutch.
In order to achieve the above object, the vehicle according to the
present invention is provided with a hydraulic clutch disposed
between a driving source and driving wheels and an automatic
transmission which is driven and controlled by a hydraulic pressure
produced from a line pressure as an original pressure. The
hydraulic clutch is actuated by a piston pressure that is produced
from the line pressure as an original pressure by a clutch
hydraulic control valve. The hydraulic clutch is disengaged by
operating a clutch hydraulic actuator to make stroke by controlling
the piston pressure as a clutch disengagement hydraulic pressure
such that an actual piston stroke position is conformed with a
target position.
In a control apparatus of this vehicle, a clutch disengagement
control section is provided. The clutch disengagement control
section is configured such that upon disengaging the hydraulic
clutch, line pressure increase control to increase the line
pressure to a value higher than a reference line pressure that is
the line pressure determined on the basis of a necessary hydraulic
pressure to ensure an operation except for a disengagement
operation of the hydraulic clutch, is started at least before the
piston pressure reaches the reference line pressure, and the line
pressure is reduced when the piston pressure is reduced during the
disengagement operation.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a whole system diagram showing a rear-wheel-drive FR
hybrid vehicle (an example of a vehicle) to which a control
apparatus according to a first embodiment of the present invention
is applied.
FIG. 2 is a sectional view showing a construction of a clutch and
motor unit section in which a first clutch CL1 (an example of a
hydraulic clutch) to be controlled to come into engagement and
disengagement by the control apparatus according to the first
embodiment is disposed.
FIG. 3 is an outer appearance diagram showing an outer pipe
connecting a first clutch hydraulic actuator that controls the
first clutch CL1 to come into engagement and disengagement and a
first clutch hydraulic control valve in the first embodiment.
FIG. 4 is a first clutch hydraulic control system diagram showing a
construction of a hydraulic control system and an electronic
control system in the first embodiment which control the first
clutch CL1 to come into engagement and disengagement.
FIG. 5 is a block diagram showing a line pressure command value
generation section which generates a line pressure command value
upon line pressure control which is executed by an AT controller in
the first embodiment.
FIG. 6 is a main flow chart showing a flow of whole processing of
generating and outputting a CL1 disengagement necessary pressure in
accordance with retention of a piston pressure command value which
is executed by an integrated controller in the first
embodiment.
FIG. 7 is a flow chart showing a flow of CL1Press value retention
processing which is executed by the integrated controller in the
first embodiment.
FIG. 8 is a flow chart showing a flow of CL1 disengagement
necessary pressure output processing which is executed by the
integrated controller in the first embodiment.
FIG. 9 is a time chart showing characteristics of vehicle speed,
rotation speed (MG rotation speed, ENG rotation speed), torque (MG
torque, ENG torque), flag (value of flags), stroke (piston stroke
signal), and hydraulic pressure (line pressure command value, line
pressure actual value, CL1 disengagement necessary pressure,
CL1Press) for explanation of an example of a first clutch
disengagement control operation in the FR hybrid vehicle in the
first embodiment.
FIG. 10 is a drive line schematic diagram showing a drive line of a
FR hybrid vehicle in which an independent second clutch is disposed
between a motor/generator and a transmission.
FIG. 11 is a drive line schematic diagram showing a drive line of a
FR hybrid vehicle in which an independent second clutch is disposed
between a transmission and driving wheels.
DESCRIPTION OF EMBODIMENTS
In the following, best modes to realize a control apparatus of a
vehicle according to the present invention are explained by
referring to the accompanying drawings.
First Embodiment
First, a construction of the control apparatus according to the
first embodiment is explained. FIG. 1 is a whole system diagram
showing a rear-wheel-drive FR hybrid vehicle (an example of a
vehicle) to which the control apparatus according to the first
embodiment of the present invention is applied. In the following,
the whole system construction is explained by referring to FIG.
1.
As shown in FIG. 1, a drive line of the FR hybrid vehicle in the
first embodiment includes engine Eng (driving source), flywheel FW,
first clutch CL1 (hydraulic clutch), motor/generator MG, second
clutch CL2, automatic transmission AT, propeller shaft PS,
differential DF, left drive shaft DSL, right drive shaft DSR, left
rear wheel RL (driving wheel), and right rear wheel RR (driving
wheel). Reference marks FL, FR, M-O/P, and S-O/P denote a left
front wheel, a right front wheel, a main oil pump, and a sub-oil
pump, respectively.
Engine Eng is a gasoline engine or a diesel engine. Engine start
control, engine stop control, etc. are carried out in accordance
with an engine control command outputted from engine controller 1.
An engine output shaft is provided with flywheel FW.
First clutch CL1 is disposed between engine Eng and motor/generator
MG. First clutch CL1 is a running mode selecting clutch which is
disengaged when an electric vehicle running mode (hereinafter
referred to as "EV mode") is selected, and is engaged when a hybrid
vehicle running mode (hereinafter referred to as "HEV mode") is
selected. A normal close dry type single plate clutch is used as
the first clutch CL1.
Motor/generator MG is disposed between first clutch CL1 and
automatic transmission AT, and has a function of operating as a
motor and a function of operating as a generator. A three-phase
alternating current synchronous motor/generator including a rotor
in which permanent magnets are embedded and a stator on which coils
are wound, is used as the motor/generator MG.
Second clutch CL2 is disposed between motor/generator MG and left
and right rear wheels RL, RR. For instance, second clutch CL2 is a
clutch provided in order to absorb torque variation by being
brought into a slip engagement condition when transmission torque
is varied as at the time of starting the engine. Second clutch CL2
is not additionally provided, but is provided by selecting a
friction engagement element disposed on a torque transmission path
from a plurality of friction engagement elements which are to be
engaged at the speed (the gear stage) selected in automatic
transmission AT.
Automatic transmission AT is, for instance, a stepwise variable
transmission which stepwise varies multiple speeds such as seven
forward speeds and one reverse speed, or a continuously variable
transmission which steplessly varies a transmission ratio. A
transmission output shaft is connected to left and right rear
wheels RL, RR via propeller shaft PS, differential DF, left drive
shaft DSL and right drive shaft DSR.
Main oil pump M-O/P is disposed on an input shaft of automatic
transmission AT, and is a mechanical oil pump which is mechanically
operated to make a pump action. Sub-oil pump S-O/P is disposed on a
unit housing or the like, and is an electric oil pump that is
operated by an electric motor when an oil amount discharged by main
oil pump M-O/P is zero, for instance, in a vehicle stop state in
the "EV mode" in which first clutch CL1 is in the disengagement
state, or when an oil amount discharged by main oil pump M-O/P is
less than a necessary oil amount.
Next, a control system of the hybrid vehicle is explained. As shown
in FIG. 1, the control system of the FR hybrid vehicle in the first
embodiment includes engine controller 1, motor controller 2,
inverter 3, battery 4, first clutch controller 5, first clutch
hydraulic control valve 6, AT controller 7, AT control valve 8,
brake controller 9, and integrated controller 10. Respective
controllers 1, 2, 5, 7, 9 are connected with integrated controller
10 through CAN communication line 11 such that they can communicate
with one another to exchange information therebetween.
Engine controller 1 receives engine rotation speed information from
engine rotation speed sensor 12, a target engine torque command
from integrated controller 10, and other necessary information.
Engine controller 1 outputs commands to control engine operating
points (Ne, Te) to a throttle valve actuator of engine Eng and the
like (engine control).
Motor controller 2 receives information from resolver 13 which
detects a rotor rotation position of motor/generator MG, a target
MG torque command and a target MG rotation speed command from
integrated controller 10, and other necessary information. Motor
controller 2 outputs commands to control motor operating points
(Nm, Tm) of motor/generator MG to inverter 3 (motor control).
Further, motor controller 2 monitors battery SOC indicative of a
charging capacity of battery 4.
First clutch controller 5 receives sensor information from piston
stroke sensor 15 which detects a piston stroke position of first
clutch hydraulic actuator 14, a target CL1 torque command from
integrated controller 10, and other necessary information. First
clutch controller 5 outputs commands to control engagement, slip
engagement, disengagement of first clutch CL1 to first clutch
hydraulic control valve 6 (first clutch control).
AT controller 7 receives information from accelerator opening
sensor 16, vehicle speed sensor 17, and other sensors 18 (a
transmission input rotation speed sensor, an inhibitor switch,
etc.). During running in a D range, AT controller 7 retrieves an
optimal speed (gear stage) on the basis of a position of an
operating point on a shift map which is determined in accordance
with accelerator opening APO and vehicle speed VSP, and outputs a
control command to obtain the retrieved speed to AT control valve 8
(shift control). In response to input of a target CL2 torque
command from integrated controller 10, AT controller 7 outputs a
slip engagement control command for second clutch CL2 to AT control
valve 8 (second clutch control). Further, AT controller 7 performs
a hydraulic shift operation of automatic transmission AT, and upon
carrying out an operation of releasing a hydraulic pressure in
first clutch CL1, AT controller 7 executes control of line pressure
PL as an original pressure to determine a maximum pressure.
Brake controller 9 receives sensor information from wheel speed
sensor 19 that detects wheel speed of each of four wheels, and from
brake stroke sensor 20, a regenerative cooperative control command
from integrated controller 10, and other necessary information.
Further, in a case where a requested braking force determined on
the basis of brake stroke BS when a brake pedal is depressed cannot
be achieved with only a regenerative braking force, brake
controller 9 serves to supplement the requested braking force by a
lacking amount thereof with a mechanical braking force
(regenerative cooperative brake control).
Integrated controller 10 has functions of managing energy
consumption of the vehicle as a whole and efficiently running the
vehicle. Integrated controller 10 receives necessary information
from motor rotation speed sensor 21 that detects motor rotation
speed Nm and from other sensors/switches 22, and information
through CAN communication line 11. Integrated controller 10 outputs
the target engine torque command to engine controller 1, the target
MG torque command and the target MG rotation speed command to motor
controller 2, the target CL1 torque command to first clutch
controller 5, the target CL2 torque command to AT controller 7, and
the regenerative cooperative control command to brake controller 9
(integrated control).
Next, referring to FIG. 2 to FIG. 5, a first clutch control system
to engage and disengage first clutch CL1 is explained. As shown in
FIG. 2, the clutch and motor unit section of the first embodiment
includes engine Eng, flywheel FW, first clutch CL1 (hydraulic
clutch), motor/generator MG, main oil pump M-O/P, automatic
transmission AT, and unit housing 30.
Unit housing 30 is connected to engine block 31 of engine Eng at a
front side thereof, and connected to transmission case 32 of
automatic transmission AT at a rear side thereof. An inside of unit
housing 30 is divided into three chambers by motor cover 33 and
stator housing 34. Flywheel FW and first clutch CL1 are disposed
within a first chamber defined by engine Eng and motor cover 33.
Motor/generator MG is disposed within a second chamber defined by
motor cover 33 and stator housing 34. Main oil pump M-O/P is
disposed within a third chamber defined by stator housing 34 and
automatic transmission AT.
First clutch CL1 is disposed between flywheel FW and hollow motor
shaft 35 of motor/generator MG. Motor/generator MG includes
resolver 13 disposed in an inside position of the rotor, and
high-voltage harness terminal 36 and cooling water inlet/outlet
port 37 which extend through unit housing 30. Main oil pump M-O/P
is driven by transmission input shaft 38 coupled to hollow motor
shaft 35.
As shown in FIG. 2 to FIG. 4, a hydraulic circuit to engage and
disengage first clutch CL1 of the first embodiment includes first
clutch hydraulic actuator 14 (clutch hydraulic actuator), first
clutch hydraulic control valve 6 (clutch hydraulic control valve),
AT control valve 8, main oil pump M-O/P, sub-oil pump S-O/P, and
oil pan 39.
First clutch hydraulic actuator 14 is a CSC hydraulic actuator that
controls engagement and disengagement of first clutch CL1. As shown
in FIG. 2 and FIG. 4, first clutch hydraulic actuator 14 includes
CSC piston 41 that slidably moves relative to CSC cylinder 40 upon
carrying out engagement and disengagement of first clutch CL1,
diaphragm spring 43 that biases CSC piston 41 in a direction in
which a volume of CSC piston chamber 42 is decreased, and oil
supply/discharge port 44 through which oil is supplied to CSC
piston chamber 42 and discharged therefrom. One end side of
diaphragm spring 43 is contacted with pressure ring 45, and the
other end side of diaphragm spring 43 is contacted with CSC piston
41 through release bearing 46. That is, when no piston pressure is
supplied to CSC cylinder 40, first clutch CL1 is held in full
engagement by a biasing force of diaphragm spring 43. On the other
hand, when a piston pressure is supplied to CSC cylinder 40, first
clutch CL1 is controlled from slip engagement to full disengagement
by controlling a stroke amount of CSC piston 41 that makes slide
movement against the biasing force of diaphragm spring 43.
Meanwhile, CSC is an abbreviation for "concentric slave
cylinder".
As shown in FIG. 2 to FIG. 4, an oil passage that connects CSC
piston chamber 42 of first clutch hydraulic actuator 14 with first
clutch hydraulic control valve 6 is constituted of inner pipe 51
that extends from oil supply/discharge port 44 to pipe connector 50
to connect them with each other, outer pipe 53 that extends from
pipe connector 50 to case mount portion 52 to connect them with
each other, case inside oil passage 54 formed in transmission case
32 to communicate with outer pipe 53, and piston pressure oil
passage 55 formed in first clutch hydraulic control valve 6 to
communicate with case inside oil passage 54. Outer pipe 53 is
supported at a mid-portion thereof on unit housing 30 by means of
clip 56.
As shown in FIG. 4, first clutch hydraulic control valve 6 is a
valve that produces the piston pressure to be supplied to CSC
piston chamber 42 of first clutch hydraulic actuator 14, from line
pressure PL as an original pressure. First clutch hydraulic control
valve 6 includes spool valve 60 and solenoid valve 61.
Spool valve 60 is a valve that receives a valve input pressure as a
valve actuating signal pressure outputted from solenoid valve 61,
and makes changeover between a drain communication side and a CSC
piston chamber communication side. Spool valve 60 includes spool
60b slidably moveable in valve bore 60a, spring 60c that biases
spool 60b leftward in FIG. 4, and valve output pressure port 60d,
valve input pressure port 60e, drain port 60f and valve actuating
pressure port 60g which are formed in valve bore 60a. Valve output
pressure port 60d is communicated with piston pressure oil passage
55. Valve input pressure port 60e is communicated with valve input
pressure oil passage 62. Drain port 60f is communicated with drain
oil passage 63. Valve actuating pressure port 60g is communicated
with valve input pressure branch oil passage 62' in which orifice
64 is disposed.
Solenoid valve 61 produces a valve input pressure (i.e., a piston
pressure) to be outputted to valve input pressure oil passage 62
from line pressure PL as an original pressure which is produced by
AT control valve 8, by an ON/OFF duty operation based on piston
pressure command value CL1Press that is outputted from first clutch
controller 5 to valve solenoid 61a.
As shown in FIG. 4, AT control valve 8 includes line pressure
solenoid 80 that produces a solenoid pressure to obtain the line
pressure based on line pressure command value LPress outputted from
AT controller 7, and pressure regulator valve 81 that regulates
line pressure PL on the basis of a pump pressure as an original
pressure and the solenoid pressure as a valve actuating signal
pressure.
As shown in FIG. 4, an electronic control system for engaging and
disengaging first clutch CL1 of the first embodiment includes first
clutch controller 5, AT controller 7 and integrated controller
10.
In a case where the "HEV mode" as the running mode is selected,
first clutch controller 5 allows first clutch CL1 to be engaged by
the biasing force of diaphragm spring 43 by outputting piston
pressure command value CL1Press (CL1Press=0) to solenoid valve 61
in accordance with an OFF command. Further, in a case where
transition of the running mode from the "HEV mode" to the "EV mode"
is carried out when running mode selecting conditions are
fulfilled, for instance, when battery SOC is sufficient and
accelerator opening APO is lower than a set threshold value, first
clutch controller 5 executes first clutch disengagement control.
Upon the first clutch disengagement control, first clutch CL1 is
allowed to shift from the slip engagement state to the full
disengagement state by outputting piston pressure command value
CL1Press (CL1Press.noteq.0) to solenoid valve 61, while monitoring
piston stroke information outputted from piston stroke sensor 15.
Further, when allowing first clutch CL1 to be in the full
disengagement state, first clutch controller 5 supplies the piston
pressure that is the line pressure PL regulated by pressure
regulator valve 81 to CSC piston chamber 42 of first clutch
hydraulic actuator 14 by outputting piston pressure command value
CL1Press based on a 100% ON duty ratio to solenoid valve 61.
AT controller 7 executes line pressure control by outputting line
pressure command value LPress to line pressure solenoid 80. Upon
the line pressure control, as shown in FIG. 5, AT controller 7
outputs line pressure command value LPress corresponding to a value
that is determined by a select-high operation selecting the highest
one of necessary pressure to disengage first clutch CL1 (i.e., CL1
disengagement necessary pressure), transmission input torque (i.e.,
T/M input torque retention necessary pressure, that is, necessary
pressure to retain T/M input torque), and minimum line pressure.
The "CL1 disengagement necessary pressure" is produced by
integrated controller 10, and outputted to AT controller 7. The
"T/M input torque retention necessary pressure" is predicted using
accelerator opening information, etc. The "minimum line pressure"
is determined on the basis of necessary pressures to ensure
engagement and disengagement operation of friction engagement
elements that are used in a shift operation in automatic
transmission AT in a non-load condition. In a case where the "CL1
disengagement necessary pressure" is not selected, line pressure
command value LPress determined by a select-high operation
selecting the highest one of the "T/M input torque retention
necessary pressure" and the "minimum line pressure" is outputted.
The line pressure PL that is obtained from line pressure command
value LPress is referred to as "reference line pressure". The
"reference line pressure" is line pressure PL that is regulated
over an entire period of time except for the disengagement time of
first clutch CL1 in which the "CL1 disengagement necessary
pressure" is selected. The "reference line pressure" is determined
so as to ensure a shift operation except for the disengagement
operation of first clutch CL1. That is, the "reference line
pressure" is regulated in accordance with the accelerator opening,
etc. as T/M input torque retention necessary pressure information.
For instance, when the accelerator opening is zero, the reference
line pressure is regulated to the minimum line pressure. As the
accelerator opening becomes higher, the reference line pressure is
regulated to a higher pressure.
FIG. 6 is a main flow chart showing a flow of a whole processing of
producing and outputting the CL1 disengagement necessary pressure
in accordance with retaining the piston pressure command value,
which is executed by integrated controller 10 in the first
embodiment (clutch disengagement control section). Referring to
FIG. 6, each of steps will be explained hereinafter.
In step S1, upon disengaging first clutch CL1, CL1Press value
retention processing (FIG. 7) of retaining piston pressure command
value CL1Press as a clutch disengagement necessary pressure signal
which is outputted from first clutch controller 5 is executed. The
flow proceeds to step S2.
In step S2, subsequent to the CL1Press value retention processing
in step S1, CL1 disengagement necessary pressure output processing
(FIG. 8) of producing the CL1 disengagement necessary pressure is
executed. The flow proceeds to END.
FIG. 7 is a flow chart showing a flow of the CL1Press value
retention processing that is executed by integrated controller 10
in the first embodiment (clutch disengagement control section).
This processing is executed in order to retain piston pressure
command value CL1Press that is outputted from first clutch
controller 5. Referring to FIG. 7, each of steps will be explained
hereinafter.
In step S101, piston pressure command value CL1Press, previous
piston pressure command value CL1PressPrevious, maximum piston
pressure retention value CL1PressMAX, stable piston pressure
retention value CL1PressStab, predetermined elapsed time flag
fTimeout, CL1 disengagement completion flag CL1_Standby, and
maximum piston pressure flag fmax are read in. The flow proceeds to
step S102. Piston pressure command value CL1Press is a read-in
signal outputted from first clutch controller 5. An initial value
of maximum piston pressure retention value CL1PressMAX is a value
to obtain a minimum necessary pressure. An initial value of stable
piston pressure retention value CL1PressStab is a value to obtain
an optimal necessary pressure. Predetermined elapsed time flag
fTimeout is rewritten to "1" when a time measured by timer fTimer
exceeds a predetermined time (for instance, three seconds).
Predetermined elapsed time flag fTimeout is returned to "0" when
timer fTimer is reset. CL1 disengagement completion flag
CL1_Standby is rewritten to "1" when first clutch CL1 is
disengaged, and is returned to "0" when first clutch CL1 is
engaged. Maximum piston pressure flag fmax is rewritten to "1" when
piston pressure command value CL1Press has reached the MAX value,
and is returned to "0" when piston pressure command value CL1Press
becomes 0 kPa.
In step S102, subsequent to the read-in operation of necessary
information in step S101, it is judged whether or not piston
pressure command value CL1Press outputted from first clutch
controller 5 is 0. If the answer to step S102 is yes (CL1Press=0),
the flow proceeds to step S103. If the answer to step S102 is no
(CL1Press.noteq.0), the flow proceeds to step S106.
In step S103, subsequent to the judgment CL1Press=0 in step S102,
timer fTimer is set to zero (timer reset). The flow proceeds to
step S104.
In step S104, subsequent to the setting fTimer=0 in step S103,
maximum piston pressure flag fmax is set to zero (reset). The flow
proceeds to step S105.
In step S105, subsequent to the setting fmax=0 in step S104,
maximum piston pressure retention value flag fCL1PressMAX is set to
zero (reset). The flow proceeds to step S115. Maximum piston
pressure retention value flag fCL1PressMAX is rewritten to "1" when
piston pressure command value CL1Press has reached a maximum value,
and is returned to "0" when piston pressure command value CL1Press
is reset.
In step S106, subsequent to the judgment CL1Press.noteq.0 in step
S102, timer fTimer is allowed to count up. The flow proceeds to
step S107.
In step S107, subsequent to the count up of fTimer in step S106, it
is judged whether or not piston pressure command value CL1Press
exceeds previous piston pressure command value CL1PressPrevious. If
the answer to step S107 is yes (CL1Press>CL1PressPrevious), the
flow proceeds to step S108. If the answer to step S107 is no
(CL1Press.ltoreq.CL1PressPrevious), the flow proceeds to step
S110.
In step S108, subsequent to the judgment
CL1Press>CL1PressPrevious in step S107, it is judged whether or
not piston pressure command value CL1Press exceeds maximum piston
pressure retention value CL1PressMAX. If the answer to step S108 is
yes (CL1Press>CL1PressMAX), the flow proceeds to step S109. If
the answer to step S108 is no (CL1Press.ltoreq.CL1PressMAX), the
flow proceeds to step S115.
In step S109, subsequent to the judgment CL1Press>CL1PressMAX in
step S108, maximum piston pressure retention value flag
fCL1PressMAX is rewritten from "0" to "1". The flow proceeds to
step S115.
In step S110, subsequent to the judgment
CL1Press.ltoreq.CL1PressPrevious in step S107, it is judged whether
or not piston pressure command value CL1Press exceeds maximum
piston pressure retention value CL1PressMAX. If the answer to step
S110 is yes (CL1Press>CL1PressMAX), the flow proceeds to step
S111. If the answer to step S110 is no
(CL1Press.ltoreq.CL1PressMAX), the flow proceeds to step S113.
In step S111, subsequent to the judgment CL1Press>CL1PressMAX in
step S110, the piston pressure command value CL1Press read in at
the current time is set to and retained as maximum piston pressure
retention value CL1PressMAX. The flow proceeds to step S112.
In step S112, subsequent to the retention of maximum piston
pressure retention value CL1PressMAX in step S111, maximum piston
pressure flag fmax is rewritten from "0" to "1". The flow proceeds
to step S115.
In step S113, subsequent to the judgment
CL1Press.ltoreq.CL1PressMAX in step S110, it is judged whether or
not piston pressure command value CL1Press is within a range which
extends from a value larger than a value obtained by subtracting
piston pressure command value offset value CL1PressOffset from
maximum piston pressure retention value CL1PressMAX to a value
smaller than a value obtained by adding piston pressure command
value offset value CL1PressOffset to maximum piston pressure
retention value CL1PressMAX. If the answer to step S113 is yes
(CL1PressMAX-CL1PressOffset<CL1Press<CL1PressMAX+CL1PressOffset),
the flow proceeds to step S114. If the answer to step S113 is no
(CL1PressMAX-CL1PressOffset.gtoreq.CL1Press, or
CL1PressMAX.gtoreq.CL1Press+CL1PressOffset), the flow proceeds to
step S115.
In step S114, subsequent to the judgment
CL1Press-CL1PressOffset<CL1Press<CL1Press+CL1PressOffset in
step S113, maximum piston pressure flag fmax is rewritten from "0"
to "1". The flow proceeds to step S115.
In step S115, subsequent to any of step S105, the judgment of no in
step S108, step S109, step S112, the judgment of no in step S113,
and step S114, the piston pressure command value CL1Press read in
at the current time is rewritten to previous piston pressure
command value CL1PressPrevious. The flow proceeds to step S116.
In step S116, subsequent to the setting of previous piston pressure
command value CL1PressPrevious in step S115, it is judged whether
or not predetermined elapsed time flag fTimeout is 1 (i.e., the
predetermined time has elapsed) or CL1 disengagement completion
flag CL1_Standby is 1 (i.e., disengagement of first clutch CL1 has
been completed). If the answer to step S116 is yes (fTimeout=1, or
CL1_Standby=1), the flow proceeds to step S117. If the answer to
step S116 is no (fTimeout=0, and CL1_Standby=0), the flow proceeds
to END.
In step S117, subsequent to the judgment fTimeout=1, or
CL1_Standby=1 in step S116, it is judged whether or not stable
piston pressure retention value CL1PressStab is smaller than piston
pressure command value CL1Press. If the answer to step S117 is yes
(CL1PressStab<CL1Press), the flow proceeds to step S118. If the
answer to step S117 is no (CL1PressStab.gtoreq.CL1Press), the flow
proceeds to END.
In step S118, subsequent to the judgment (CL1PressStab<CL1Press)
in step S117, the piston pressure command value CL1Press read in at
the current time is set to stable piston pressure retention value
CL1PressStab. The flow proceeds to END.
FIG. 8 is a flow chart showing a flow of the CL1 disengagement
necessary pressure output processing that is executed by integrated
controller 10 in the first embodiment (clutch disengagement control
section). This processing is executed in order to reflect the CL1
disengagement necessary pressure on line pressure command value
LPress. Referring to FIG. 8, each of steps will be explained
hereinafter.
In step S201, piston pressure command value CL1Press, previous
piston pressure command value CL1PressPrevious, maximum piston
pressure retention value CL1PressMAX, stable piston pressure
retention value CL1PressStab, predetermined elapsed time flag
fTimeout, CL1 disengagement completion flag CL1_Standby, maximum
piston pressure flag fmax, and piston pressure command value offset
value CL1PressOffset are read in. The flow proceeds to step
S202.
In step S202, subsequent to the read-in operation of necessary
information in step S201, it is judged whether or not piston
pressure command value CL1Press outputted from integrated
controller 10 is 0. If the answer to step S202 is yes (CL1Press=0),
the flow proceeds to step S203. If the answer to step S202 is no
(CL1Press.noteq.0), the flow proceeds to step S204.
In step S203, subsequent to the judgment CL1Press=0 in step S202,
the CL1 disengagement necessary pressure is set to zero, this
information "CL1 disengagement necessary pressure=0" is outputted
to AT controller 7. The flow proceeds to END.
In step S204, subsequent to the judgment CL1Press.noteq.0 in step
S202, it is judged whether or not maximum piston pressure flag fmax
is 1. If the answer to step S204 is yes (fmax=1), the flow proceeds
to step S205. If the answer to step S204 is no (fmax=0), the flow
proceeds to step S206.
In step S205, subsequent to the judgment fmax=1 in step S204, the
CL1 disengagement necessary pressure is set to piston pressure
command value CL1Press, and this information "CL1 disengagement
necessary pressure=CL1Press" is outputted to AT controller 7. The
flow proceeds to END.
In step S206, subsequent to the judgment fmax=0 in step S204, it is
judged whether or not predetermined elapsed time flag fTimeout is 1
(i.e., the predetermined time has elapsed) or CL1 disengagement
completion flag CL1_Standby is 1 (i.e., disengagement of first
clutch CL1 has been completed). If the answer to step S206 is yes
(fTimeout=1, or CL1_Standby=1), the flow proceeds to step S207. If
the answer to step S206 is no (fTimeout=0, and CL1_Standby=0), the
flow proceeds to step S208.
In step S207, subsequent to the judgment fTimeout=1, or
CL1_Standby=1 in step S206, the CL1 disengagement necessary
pressure is set to stable piston pressure retention value
CL1PressStab, and this information "CL1 disengagement necessary
pressure=CL1PressStab is outputted to AT controller 7. The flow
proceeds to END.
In step S208, subsequent to the judgment fTimeout=0, and
CL1_Standby=0 in step S206, it is judged whether or not maximum
piston pressure retention value flag fCL1PressMAX is 1. If the
answer to step S208 is yes (fCL1PressMAX=1), the flow proceeds to
step S209. If the answer to step S208 is no (fCL1PressMAX=0), the
flow proceeds to step S210.
In step S209, subsequent to the judgment fCL1PressMAX=1 in step
S208, the CL1 disengagement necessary pressure is set to a value
obtained by adding piston pressure command value offset value
CL1PressOffset to piston pressure command value CL1Press, and this
information "CL1 disengagement necessary
pressure=CL1Press+CL1PressOffset" is outputted to AT controller 7.
The flow proceeds to END.
In step S210, subsequent to the judgment fCL1PressMAX=0 in step
S208, the CL1 disengagement necessary pressure is set to maximum
piston pressure retention value CL1PressMAX, and this information
"CL1 disengagement necessary pressure=CL1PressMAX" is outputted to
AT controller 7. The flow proceeds to END.
Next, an operation of the control apparatus of a FR vehicle
according to the first embodiment is explained. The operation is
described individually with respect to "CL1Press value retention
processing operation", "CL1 disengagement necessary pressure output
processing operation", "first clutch disengagement control
operation" and "line pressure increase control start timing setting
operation".
[CL1Press Value Retention Processing Operation]
In a case where first clutch CL1 is in the engagement state by
selecting the "HEV mode", piston pressure command value CL1Press is
0. Accordingly, in the flow chart as shown in FIG. 7, the flow
successively proceeds to step S101, step S102, step S103, step
S104, step S105, step S115, step S116 and END. In step S103, timer
fTimer is set to 0 (timer reset). In step S104, maximum piston
pressure flag fmax is set to 0 (reset). In step S105, maximum
piston pressure retention value flag fCL1PressMAX is set to 0
(reset). Further, in step S115, the piston pressure command value
CL1Press read-in at current time is rewritten to previous piston
pressure command value CL1PressPrevious.
In accordance with transition from the "HEV mode" to the "EV mode",
piston pressure command value CL1Press (.noteq.0) is outputted from
first clutch controller 5 so that increase in piston pressure is
started in order to disengage first clutch CL1. In this condition,
the flow that successively proceeds to step S101, step S102, step
S106, step S107, step S108, step S115, step S116 and END in the
flow chart as shown in FIG. 7, is repeated until piston pressure
command value CL1Press exceeds maximum piston pressure retention
value CL1PressMAX.
When piston pressure command value CL1Press exceeds maximum piston
pressure retention value CL1PressMAX in accordance with a
continuous increase in piston pressure command value CL1Press, the
flow that successively proceeds to step S101, step S102, step S106,
step S107, step S108, step S109, step S115, step S116 and END in
the flow chart as shown in FIG. 7, is repeated. In step S109,
maximum piston pressure retention value flag fCL1PressMAX is
rewritten from "0" to "1".
In a case where piston pressure command value CL1Press is larger
than maximum piston pressure retention value CL1PressMAX under a
condition that the increase in piston pressure command value
CL1Press is stopped and piston pressure command value CL1Press has
changed toward a side on which the value CL1Press is hold or
decreased, the flow that successively proceeds to step S101, step
S102, step S106, step S107, step S110, step S111, step S112, step
S115, step S16 and END in the flow chart as shown in FIG. 7, is
repeated. In step S111, the piston pressure command value CL1Press
read in at the current time is newly set to maximum piston pressure
retention value CL1PressMAX and retained. In step S112, maximum
piston pressure flag fmax is rewritten from "0" to "1".
On the other hand, in a case where piston pressure command value
CL1Press is not larger than maximum piston pressure retention value
CL1PressMAX and the following expression:
"CL1Press-CL1PressOffset<CL1Press<CL1Press+CL1PressOffset" is
satisfied when piston pressure command value CL1Press has changed
toward the side on which the value CL1Press is hold or decreased,
the flow that successively proceeds to step S101, step S102, step
S106, step S107, step S110, step S113, step S114, step S115, step
S116 and END in the flow chart as shown in FIG. 7, is repeated. In
step S114, maximum piston pressure flag fmax is rewritten from "0"
to "1". Further, in a case where the following expression:
"CL1Press-CL1PressOffset<CL1Press<CL1Press+CL1PressOffset" is
not satisfied, the flow that successively proceeds to step S101,
step S102, step S106, step S107, step S110, step S113, step S115,
step S116 and END in the flow chart as shown in FIG. 7, is
repeated.
After that, in a case where the predetermined elapsed time
condition is fulfilled (fTimeout=1) or the first clutch CL1
disengagement completion condition is fulfilled (CL1_Standby=1),
and it is judged that stable piston pressure retention value
CL1PressStab is smaller than piston pressure command value
CL1Press, the flow proceeds from step S115 through step S116, step
S117, step S118 to END in the flow chart as shown in FIG. 7. In
step S118, the piston pressure command value CL1Press read in at
the current time is set to stable piston pressure retention value
CL1PressStab.
In this CL1Press value retention processing, a first function
thereof is to compare piston pressure command value CL1Press
outputted from first clutch controller 5 with a maximum value
(CL1PressMAX) among past piston pressure command value CL1Press
(step S110), and update maximum piston pressure retention value
CL1PressMAX if CL1Press exceeds CL1PressMAX (step S111). For
instance, if maximum piston pressure retention value CL1PressMAX is
not updated, the conventional maximum value will be kept retained
so that a needlessly high necessary pressure will be used. Further,
a memory may be separately provided to continue memorizing the
maximum value even at ignition-off time. However, in such a case,
since the relationship between piston pressure command value and
actual piston pressure is changed depending on a temperature
condition, it is likely that a needlessly high necessary pressure
is used. Therefore, it is desirable to suppress continuing
memorizing the maximum value. In contrast, in the CL1Press value
retention processing according to the first embodiment, a minimum
value of the CL1 disengagement necessary pressure is to be used as
an initial value of maximum piston pressure retention value
CL1PressMAX, and maximum piston pressure retention value
CL1PressMAX is to be reset at ignition-off time. As a result, it is
possible to avoid using a needlessly high necessary pressure.
In this CL1Press value retention processing, a second function
thereof is to retain stable piston pressure command value CL1Press
after disengagement of first clutch CL1. In order to realize this
function, in a case where the condition that CL1 disengagement
completion flag CL1_Standby as a signal indicating the judgment of
completion of first clutch CL1 disengagement becomes "1" after
piston pressure command value CL1Press is started to increase by a
request for disengagement of first clutch CL1, or the condition
that predetermined elapsed time flag fTimeout as an internal
arithmetic value becomes "1" after a certain time has elapsed from
the time at which piston pressure command value CL1Press becomes a
value larger than 0, is fulfilled, i.e., the OR condition is
established (yes in step S116), and piston pressure command value
CL1Press exceeds an initial value after becoming stable (yes in
step S117), the value as the stable value is updated (step S118).
It is desirable that CL1 disengagement completion flag CL1_Standby
is outputted from first clutch controller 5 that includes piston
stroke sensor 15 for first clutch CL1 and has a target value of CL1
disengagement stroke amount, and actually computes piston pressure
command value CL1Press. Further, in a case where CL1 disengagement
completion flag CL1_Standby indicating "1" is not outputted for a
predetermined time, predetermined elapsed time flag fTimeout is
used to hold piston pressure command value CL1Press at that time as
a stable value. Therefore, it is actually undesired that
predetermined elapsed time flag fTimeout other than "1" is
outputted.
[CL1 Disengagement Necessary Pressure Output Processing
Operation]
The CL1 disengagement necessary pressure output processing and the
CL1Press value retention processing are simultaneously executed. In
a case where first clutch CL1 is in the engagement state by
selecting the "HEV mode", piston pressure command value CL1Press is
0. Accordingly, in the flow chart as shown in FIG. 8, the flow
successively proceeds to step S201, step S202, step S203 and END.
In step S203, the CL1 disengagement necessary pressure is set to
zero, and this information "CL1 disengagement necessary pressure=0"
is outputted to AT controller 7.
In a case where piston pressure command value CL1Press becomes
nonzero (CL1Press.noteq.0) and the following expressions: "fmax=0",
"fTimeout=0", "CL1_Standby=0", "fCL1PressMax=0" are satisfied, the
flow successively proceeds to step S201, step S202, step S204, step
S206, step S208, step S210 and END in the flow chart as shown in
FIG. 8. In step S210, the CL1 disengagement necessary pressure is
set to maximum piston pressure retention value CL1PressMAX, and
this information "CL1 disengagement necessary pressure=CL1PressMAX"
is outputted to AT controller 7.
After that, when piston pressure command value CL1Press exceeds
maximum piston pressure retention value CL1PressMAX, and maximum
piston pressure retention value flag fCL1PressMAX is rewritten to 1
(fCL1PressMAX=1), the flow successively proceeds to step S201, step
S202, step S204, step S206, step S208, step S209 and END in the
flow chart as shown in FIG. 8. In step S209, the CL1 disengagement
necessary pressure is set to a value obtained by adding piston
pressure command value offset value CL1PressOffset to piston
pressure command value CL1Press, and this information "CL1
disengagement necessary pressure=CL1Press+CL1PressOffset" is
outputted to AT controller 7.
In a case where maximum piston pressure flag fmax is rewritten to 1
(fmax=1) when piston pressure command value CL1Press exceeds
maximum piston pressure retention value CL1PressMAX or reaches
approximately maximum piston pressure retention value CL1PressMAX,
the flow successively proceeds to step S201, step S202, step S204,
step S205 and END in the flow chart as shown in FIG. 8. In step
S205, the CL1 disengagement necessary pressure is set to piston
pressure command value CL1Press, and this information "CL1
disengagement necessary pressure=CL1Press" is outputted to AT
controller 7.
In a case where the disengagement operation of first clutch CL1 has
completed and first clutch CL1 is brought into the stable state,
and the expression "fTimeout=1" (predetermined elapsed time
condition) or the expression "CL1_Standby=1" (first clutch CL1
disengagement completion condition) is satisfied, the flow
successively proceeds to step S201, step S202, step S204, step
S206, step S207 and END in the flow chart as shown in FIG. 8. In
step S207, the CL1 disengagement necessary pressure is set to
stable piston pressure retention value CL1PressStab, and this
information "CL1 disengagement necessary pressure=CL1PressStab" is
outputted to AT controller 7.
In this CL1 disengagement necessary pressure output processing, a
first function thereof resides in that when piston pressure command
value CL1Press becomes higher than 0, maximum piston pressure
retention value CL1PressMAX that is a maximum retention value is
outputted as the "CL1 disengagement necessary pressure" (step
S210). When the "CL1 disengagement necessary pressure" is thus
outputted at the time at which piston pressure command value
CL1Press becomes higher than 0, the "CL1 disengagement necessary
pressure" is reflected on line pressure command value LPress such
that pressure regulator valve 81 on an upstream side of main oil
pump M-O/P, and sub-oil pump S-O/P are controlled to raise line
pressure PL up to line pressure command value LPress. However, line
pressure PL is not immediately raised in response to line pressure
command value LPress, and line pressure PL is raised with a certain
delay. The reasons therefor are oil temperature, increase in oil
leakage amount which is caused by a clearance expanded due to
variation and deterioration in components such as main oil pump
M-O/P, pressure regulator valve 81, sub-oil pump S-O/P, etc., and
the like. Accordingly, a rise in actual line pressure is advanced
or retarded, and therefore, timing of raising line pressure command
value LPress can be suitably advanced or retarded. However, if line
pressure command value LPress is too early outputted, line pressure
PL will become needlessly high to thereby increase a lubricating
oil amount in automatic transmission AT. As a result, an increase
in friction might be caused, thereby exerting an adverse influence
upon fuel economy. Further, if line pressure command value LPress
is too late outputted, an actual pressure may become lower than a
necessary pressure for piston pressure command value CL1Press due
to a delay between command pressure and actual pressure. As a
result, there occurs a delay in disengagement time of first clutch
CL1, and the like. In consideration of these risks, it is desired
that when piston pressure command value CL1Press becomes higher
than 0, line pressure command value LPress based on maximum piston
pressure retention value CL1PressMAX as a MAX value is
outputted.
In the CL1 disengagement necessary pressure output processing, a
second function resides in that when piston pressure command value
CL1Press exceeds a maximum value, the "CL1 disengagement necessary
pressure" is reduced in accordance with piston pressure command
value CL1Press (step S205, step S209). That is, since a delay
between command pressure and actual pressure occurs, the "CL1
disengagement necessary pressure" itself to be used in the line
pressure control is synchronized with piston pressure command value
CL1Press in order to reduce an unnecessary line pressure as quick
as possible. The judgment as to whether or not piston pressure
command value CL1Press has reached a highest value is executed
using internal flags that are maximum piston pressure flag fmax and
maximum piston pressure retention value flag fCL1PressMAX in the
flow chart as shown in FIG. 8.
In the CL1 disengagement necessary pressure output processing, a
third function thereof resides in that when disengagement of first
clutch CL1 has completed in accordance with piston pressure command
value CL1Press, and first clutch CL1 is in the stable state, stable
piston pressure retention value CL1PressStab that is a value to be
retained as a stable value is commanded as the "CL1 disengagement
necessary pressure" (step S207). As described above, the second
function is to output piston pressure command value CL1Press as the
"CL1 disengagement necessary pressure" after piston pressure
command value CL1Press becomes the highest value. However, in a
case where maximum piston pressure flag fmax which is raised when
piston pressure command value CL1Press has reached the highest
value is "0", the highest value will continue to be outputted by
the first function so that the line pressure is maintained high to
thereby cause deterioration in fuel economy. Therefore, assuming
that maximum piston pressure flag fmax does not become "1", the CL1
disengagement completion judgment is executed to output stable
piston pressure retention value CL1PressStab in a case where the a
condition that CL1 disengagement completion flag CL1_Standby that
is transmitted from integrated controller 10 to AT controller 7
becomes "1", or the condition that predetermined elapsed time flag
fTimeout as an internal arithmetic value becomes "1" after a
certain time has elapsed from the time at which piston pressure
command value CL1Press becomes a value larger than 0, i.e., the OR
condition, is fulfilled, thereby suppress deterioration in fuel
economy.
[First Clutch Disengagement Control Operation]
As described above, when the "CL1 disengagement necessary pressure"
is outputted from integrated controller 10 to AT controller 7, in
AT controller 7 to which the "CL1 disengagement necessary pressure"
is inputted, line pressure command value LPress is generated by a
select-high operation selecting the highest one of the "CL1
disengagement necessary pressure", the "T/M input torque retention
necessary pressure" and the "minimum line pressure" as shown in
FIG. 5. Line pressure command value LPress is then outputted to
line pressure solenoid 80 to thereby execute line pressure
control.
On the other hand, when the running mode judgment to shift from the
"HEV mode" to "EV mode" is executed in integrated controller 10,
the "CL1 disengagement command" is outputted from integrated
controller 10 to first clutch controller 5. In first clutch
controller 5 to which the "CL1 disengagement command" is inputted,
piston pressure command value CL1Press is generated by feedback
control to eliminate a difference between a target piston stroke
and an actual piston stroke from piston stroke sensor 15. Piston
pressure command value CL1Press is then outputted to solenoid valve
61 to thereby execute the first clutch disengagement control.
Accordingly, the first clutch disengagement control by monitoring
the piston stroke is executed in cooperation with the line pressure
increase control that is executed when the "CL1 disengagement
necessary pressure" is selected upon the line pressure control. The
first clutch disengagement control operation which is carried out
upon disengaging first clutch CL1 in accordance with the judgment
of mode transition from the "HEV mode" to the "EV mode" during the
vehicle running at a constant speed, will be explained hereinafter
by referring to a time chart as shown in FIG. 9.
At time t1, piston pressure command value CL1Press becomes 0, and
the piston pressure begins to raise. In the same timing, i.e., at
time t1, the "CL1 disengagement necessary pressure" based on
maximum piston pressure retention value CL1PressMAX that is the
past maximum retention value is outputted, and line pressure
command value LPress corresponding to the "CL1 disengagement
necessary pressure" is outputted. At time t2, the piston pressure
becomes a maximum pressure, and piston pressure command value
CL1Press exceeds maximum piston pressure retention value
CL1PressMAX. After that, the "CL1 disengagement necessary pressure"
is gradually reduced in accordance with gradual reduction of piston
pressure command value CL1Press. From time t2.at which maximum
piston pressure command value flag fCL1PressMAX is rewritten from
"0" to "1" to time t3 at which the judgment of completion of
disengagement of first clutch CL1 is made, line pressure command
value LPress and line pressure actual value exhibit characteristics
that they are gradually reduced in accordance with the gradual
reduction of the "CL1 disengagement necessary pressure". At time t3
at which CL1 disengagement completion judgment flag CL1_Standby is
rewritten from "0" to "1", stable piston pressure retention value
CL1PressStab as the "CL1 disengagement necessary pressure" is
outputted, so that line pressure command value LPress and line
pressure actual value vary following the "CL1 disengagement
necessary pressure" and exhibit a level-off characteristic.
Accordingly, in a case where a drop of the piston pressure is
caused, for instance, due to deterioration in sealing properties of
hydraulic components, etc., when disengaging first clutch CL1,
there is gained an experience that the "CL1 disengagement necessary
pressure" exceeds the reference line pressure determined by a
select-high operation selecting the higher one of the "T/M input
torque retention necessary pressure" and the "minimum line
pressure". With this experience, when disengagement of first clutch
CL1 is carried out at the next time or later, the line pressure
increase control to increase the line pressure to a value higher
than the reference line pressure in advance is started with a
timing at least before the piston pressure reaches the reference
line pressure. Thus, when the experience of lack of the line
pressure is gained, learning control to previously start the line
pressure increase control is executed on the basis of this
experience. As a result, upon disengaging first clutch CL1, a delay
in rise in the line pressure can be eliminated to thereby enhance a
response of disengagement of first clutch CL1.
This line pressure increase control is started at least before the
piston pressure reaches the reference line pressure, and ended by
returning the line pressure to the reference line pressure when the
piston pressure is dropped during the disengagement operation. That
is, the line pressure increase control is not the control to shift
the reference line pressure to an increase side thereof, but the
control to temporarily increase the line pressure only with a
necessary timing for a necessary time period. Therefore, even when
the experience that the "CL1 disengagement necessary pressure"
exceeds the reference line pressure is accumulated upon disengaging
first clutch CL1, any change in setting the reference line pressure
is not necessary, whereby any unnecessary energy loss can be
suppressed as compared to a case where the reference line pressure
is set high in expectation of an increment of the piston
pressure.
[Operation of Setting Start Timing of Line Pressure Increase
Control]
As described above, during the first clutch disengagement control,
information on the "CL1 disengagement necessary pressure" is
generated by integrated controller 10 and outputted to AT
controller 7. In AT controller 7 to which the "CL1 disengagement
necessary pressure" is inputted, the "CL1 disengagement necessary
pressure" is selected to thereby determine line pressure command
value LPress and execute the line pressure increase control.
Accordingly, the feature of the present invention basically resides
in that the information on the "CL1 disengagement necessary
pressure" generated by integrated controller 10 is presented to AT
controller 7 only with a necessary timing for a necessary time
period in order to suppress unnecessary energy loss and ensure the
disengagement operation of first clutch CL1 with a good response.
Therefore, it is important how to determine a timing of starting
the presentation of the "CL1 disengagement necessary pressure" and
a timing of ending the presentation thereof.
The timing of starting the presentation of the "CL1 disengagement
necessary pressure" can be set to any timing within a time width
that includes the timing of starting to increase the piston
pressure and covers times before and after the timing of starting
to increase the piston pressure. In this case, it is possible to
fully ensure the "CL1 disengagement necessary pressure" by starting
the line pressure increase control within the time width that
straddles the timing of starting to increase the piston pressure in
expectation of a response delay between line pressure command value
LPress and the line pressure actual value. In a case where a timing
of starting to increase the line pressure is set to before the
timing of starting to increase the piston pressure (piston pressure
command value CL1press), the line pressure can be increased in
advance with a timing at which it is found that disengagement of
first clutch CL1 (uncoupling of engine Eng and motor/generator MG)
is necessary, for instance, with a timing of the judgment of mode
transition to the "EV mode". Further, in a case where the timing of
starting to increase the line pressure is set to after the timing
of starting to increase the piston pressure (piston pressure
command value CL1Press), the timing of starting to increase the
line pressure can be afterward offset from the timing of starting
to increase the piston pressure within such a range that the line
pressure actual value is not lower than a piston pressure actual
value in hydraulic curves as shown in FIG. 9. If the timing of
starting to increase the line pressure is too late, a peak of the
curve of the line pressure actual value will be retarded so that
the piston pressure (CL1press) actual value cannot reach the "CL1
disengagement necessary pressure". The curve of increase in the
line pressure actual value is variable depending on conditions such
as a length of a hydraulic path, a viscosity of a working oil, etc.
Therefore, in a case where the timing of starting to increase the
line pressure is afterward offset from the timing of starting to
increase the piston pressure, it is preferred to previously
determine the timing of starting to increase the line pressure such
that the piston pressure (CL1press) actual value surely reaches the
line pressure actual value based on the "CL1 disengagement
necessary pressure", by an experiment, etc.
In the first embodiment, commanding the "CL1 disengagement
necessary pressure" is started (that is, the line pressure increase
control is started) in conformity with the timing of starting to
increase piston pressure command value CL1Press that indicates the
piston pressure. The reason therefor is as follows. If line
pressure command value LPress is increased before the timing of
increasing piston pressure command value CL1Press, the line
pressure will be increased even over a unnecessary time period,
thereby causing an increase in lubricating oil amount which causes
an increase in friction. As a result, an increase in energy loss
will be caused. On the other hand, if line pressure command value
LPress is increased after the timing of increasing piston pressure
command value CL1Press, a rise in line pressure can be retarded to
thereby suppress an increase in friction due to an increased
lubricating oil amount which is caused due to an unnecessary
increase in line pressure. As a result, energy loss can be reduced.
However, there occurs a possibility of failing to ensure a
necessary pressure to disengage first clutch CL1. In contrast, if
line pressure command value LPress is increased at the same timing
as the timing of increasing piston pressure command value CL1Press,
these timings can be set at an optimal point without these risks
such that a necessary pressure to disengage first clutch CL1 can be
ensured without causing an increase in energy loss. Further, in the
first embodiment, on the basis of the judgment of mode transition
from the "EV mode" to "HEV mode", commanding the "CL1 disengagement
necessary pressure" is to be ended (that is, the line pressure
increase control is to be ended) in conformity with the timing at
which piston pressure command value CL1Press is changed from
nonzero (CL1Press.noteq.0) to zero (CL1Press=0).
Next, effects that can be obtained in the control apparatus of a FR
vehicle according to the first embodiment will be explained
hereinafter.
(1) A control apparatus of a vehicle (FR hybrid vehicle) including
a hydraulic clutch (first clutch CL1) disposed between a driving
source (engine Eng) and left and right rear wheels RL, RR (driving
wheels) and automatic transmission AT that is driven and controlled
by a hydraulic pressure produced from line pressure PL as an
original pressure, the hydraulic clutch (first clutch CL1) being
actuated by a piston pressure that is produced from the line
pressure as an original pressure by a clutch hydraulic control
valve (first clutch hydraulic control valve 6), the hydraulic
clutch being disengaged by operating a clutch hydraulic actuator
(first clutch hydraulic actuator 14) to make stroke by controlling
the piston pressure as a clutch disengagement hydraulic pressure
such that an actual piston stroke position is conformed with a
target position, the control apparatus including a clutch
disengagement control section (FIG. 6, FIG. 7, FIG. 8) which is
configured such that in a case where, upon disengaging the
hydraulic clutch (first clutch CL1), there is gained an experience
that a clutch disengagement necessary pressure exceeds a reference
line pressure that is line pressure PL determined on the basis of a
necessary hydraulic pressure to ensure an operation except for a
disengagement operation of the hydraulic clutch (first clutch CL1),
line pressure increase control to increase line pressure PL to a
value higher than the reference line pressure in advance is started
at least before the piston pressure reaches the reference line
pressure when carrying out disengagement of the hydraulic clutch
(first clutch CL1) at the next time or later, and line pressure PL
is reduced when the piston pressure is reduced during this
disengagement operation.
With this construction, when disengaging the clutch (first clutch
CL1), it is possible to enhance a response of clutch disengagement
regardless of variation in clutch disengagement necessary pressure
(CL1 disengagement necessary pressure) while suppressing
unnecessary energy loss.
(2) The clutch disengagement control section (FIG. 7, FIG. 8) is
configured to set a timing of increasing line pressure PL within a
predetermined time width that straddles a timing of starting to
increase the piston pressure (piston pressure command value
CL1Press). With this configuration, in addition to the above effect
(1), it is possible to set the timing of increasing line pressure
PL to a timing of ensuring a necessary pressure to disengage first
clutch CL1 in expectation of a hydraulic response delay between
line pressure command value LPress and a line pressure actual
value.
(3) The clutch disengagement control section (FIG. 7, FIG. 8) is
configured to set a timing of increasing line pressure PL in
conformity with the timing of starting to increase the piston
pressure (piston pressure command value CL1Press). With this
configuration, in addition to the above effect (2), the timing of
increasing line pressure PL can be set to an optimal timing in
which the necessary pressure to disengage first clutch CL1 can be
ensured without causing an increase in energy loss.
Although the control apparatus of a vehicle according to the
present invention is explained above on the basis of the first
embodiment, the specific construction of the present invention is
not limited to the first embodiment. Variations and modifications
of the first embodiment will be made without departing from the
scope of the present invention which is defined with reference to
the following claims.
In the first embodiment, the reference line pressure is determined
on the basis of a necessary hydraulic pressure to ensure engagement
and disengagement operations of a friction engagement element that
is used upon shifting a speed in automatic transmission AT.
However, in a case where a power split mechanism, a clutch
mechanism, etc. except for an automatic transmission are disposed
between the driving source and the driving wheels, the reference
line pressure may be determined on the basis of a necessary
hydraulic pressure to ensure an operation of these mechanisms.
In the first embodiment, the timing of starting the line pressure
increase control is set in conformity with the timing of starting
to increase a piston pressure command value (CL1Press). However,
the timing of starting the line pressure increase control may be
set within a predetermined time width that straddles the timing of
starting to increase the piston pressure or the piston pressure
command value CL1Press. That is, the timing of starting the line
pressure increase control and the timing of ending the line
pressure increase control are not particularly limited to those in
the first embodiment if when carrying out disengagement of the
hydraulic clutch, the line pressure increase control to increase
the line pressure to a value higher than the reference line
pressure in advance is started before the clutch disengagement
hydraulic pressure reaches the reference line pressure, and the
line pressure is returned to the reference line pressure when the
piston pressure is reduced during this disengagement operation.
In the first embodiment, integrated controller 10 receives piston
pressure command value CL1Press outputted from first clutch
controller 5, generates the "CL1 disengagement necessary pressure",
and transmits the generated "CL1 disengagement necessary pressure"
to AT controller 7. However, first clutch controller 5 or AT
controller 7 may be configured to generate the "CL1 disengagement
necessary pressure" and execute the line pressure control.
In the first embodiment, the control apparatus is applied to the "1
motor+2 clutches" FR hybrid vehicle. However, the control apparatus
may be applied to a "1 motor+2 clutches" FF hybrid vehicle.
Further, the control apparatus may be applied to a hybrid vehicle
in which second clutch CL2 and automatic transmission AT of the
first embodiment are omitted. Further, the control apparatus may be
applied to an electric vehicle and an engine vehicle each including
a hydraulic clutch and any other hydraulically operating mechanism
which are disposed between a driving source and driving wheels.
In the first embodiment, one of the friction engagement elements
built in automatic transmission AT is used as second clutch CL2
that is a starting clutch. However, as shown in FIG. 10,
independent second clutch CL2 may be arranged between
motor/generator MG and automatic transmission AT. Further, as shown
in FIG. 11, independent second clutch CL2 may be arranged between
automatic transmission AT and driving wheels RL, RR.
As described above, in the control apparatus according to the
present invention, in a case where a drop in piston pressure is
caused, for instance, due to deterioration in sealing properties of
hydraulic components, etc., upon disengaging the hydraulic clutch,
there is gained an experience that the clutch disengagement
necessary pressure exceeds the reference line pressure. With this
experience, when disengagement of the hydraulic clutch is carried
out at the next time or later, the line pressure increase control
to increase the line pressure to a value higher than the reference
line pressure in advance is started with a timing at least before
the piston pressure reaches the reference line pressure. Thus, when
the experience of lack of the line pressure is gained, the line
pressure increase control is executed in accordance with learning
control based on this experience. As a result, upon disengaging the
clutch, a delay in rise in line pressure can be eliminated to
thereby enhance a response of disengagement of the clutch.
This line pressure increase control is started at least before the
piston pressure reaches the reference line pressure, and ended by
reducing the line pressure when the piston pressure is reduced
during the disengagement operation. That is, the line pressure
increase control is the control to temporarily increase the line
pressure only with a necessary timing for a necessary time period,
but it is not the control to shift the reference line pressure
itself to an increase side thereof. Therefore, even when the
experience that the disengagement necessary pressure exceeds the
reference line pressure is repeated and accumulated at the times of
disengaging the clutch, any change in setting the reference line
pressure is not necessary, and unnecessary energy loss can be
suppressed as compared to a case where the reference line pressure
is set high in expectation of an increment of the piston pressure.
As a result, upon disengaging the clutch, a response of clutch
disengagement can be enhanced regardless of variation in clutch
disengagement necessary pressure, while suppressing unnecessary
energy loss.
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